Improvement in safety device for mainsprings



J. J. THORNTON.

SAFETY DEVICE FUR MAIN-SPRINGS N0.174, 031. Patented IBb- ,1876.

N, FEVERS, PMOTO-LITNOGRAPHER, WASHINGTON. D

UNITED STATES PATENT OFFICE.

JOHN J. THORNTON, OFOLEVELAND, OHIO, ASSIGNOR OF ONE-HALF HIS RIGHT TODANIEL H. RIDGVVAY, OF SAME PLACE.

IMPROVEMENT IN SAFETY DEVICE FOR MAlNSPRINGS.

Specification forming partof Letters Patent No. 174.03 I, dated February22, 1876; application tiled February 16, 1874.

T 0 all whom it may concern:

Be it know that I, JOHN J. THORNTON, of Cleveland. in the county ofOuyahoga and .State of Ohio, have invented an Improvement The object ofthis invention is an improve ment upon the watch-barrels having aninternal hoop, to which one end of the main'spring is attached, adaptedto move in one direction independently of the barrel and in the otherdirection with such barrel; and it consists in the peculiar constructionof the hoop, and, further in the combination of such hoop and, thepeculiar watch'barrel, as more fully hereinafter explained.

Figure l is a plan View of the mainspring barrel, the cover and thespring being removed. Fig. 2 is a similar view with the spring and hoopin place. Fig.3 is a crosssection at a: as in Fig. 2, with the cover andwindingpost in place. Fig. 4 is an enlarged side elevation of the hoop,showing the bottom sloping point and the top spring of one vside. Fig. 5is asimilar view of the hoop,

showing the hook from the outside. Fig. 6 is a perspective view of theinainspring.

In the drmving, A represents the main spring-barrel, provided with theusual cover, A, through which is inserted and secured the winding-post,a. The lower periphery is toothed in the usual manner, and on oppositeside two slots, 1) b, are cut through the bot tom. The cup-is confinedin place by spring ing it into a shallow bezel in the internal walls ofthe barrel. B is a metal hoop, loosely fitted into the barrel, and inits side a tongue, 0, is punched to project inwardly and form the hookfor the outer end of the mainspring U, which has a slot cut in it toslip over the hook.

The inner end is slotted-to slip over a stud on the winding-post, in theusual manner. At. opposite sides'two sloping points, at d, are formed onthe lower periphery of the hoop, which drop into the slots b b of thebarrel when the hoop is inserted therein, engaging with the barrel andcarrying it forward so long as the tension is in the spring; but, if thespring breaks and recoils, these points rise out of the slots when thehoop revolves in the barrel, which not only is motionless, but is notsubjected to the impact of the spring, which is taken by the hoop. e eare two springs split upfrom the upper periphery of the hoop, againstwhich the cover lightly rests, to.keep the hoop in place'inthe bottom ofthe barrel.

The principal advantages of my device lie in its simplicity, the severalparts being all in one piece, and not liable to get out of order, andits efficiency in operation.

What I claim as my invention, and desire to secure by Letters Patent,is-

1. The hoop B, adapted for the purposes set forth, provided with thedownwardly-projecting points d d, the tongue 0, and the springs e c, allconstructed and arranged substantially as described and shown.

2. In combination, the spring-barrel A, having the slots 1) b cutthrough its bottom, and the hoop B, having the downwardly-projectingpoints (1 d, adapted to enter the said slots, the springs e 6, adaptedto press against the cover of the spring-barrel, and the tongue 0 forthe reception of the end of the mainspring, all constructed, arranged,and operating substantially as described and shown.

JNO. JIBB THORNTON.

Witnesses:

'1. Games, J. LAWRENCE.

